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Monday, 5 April 2010

A PIC16C84-microcontroller is the mastermind in this project and controls the whole operation. Taking advantageof the PIC16C84's internal EEPROM (electrically erasable programmable read onlymemory), a data store and recall facility have been programmed in as well. There is also a masking option that allows foreground echoes to be ignored.The device can record and recall 30 or 32 distance measurements, allowing several readings to be taken before copying them to paper - ideal when taking measurements in difficult to access locations. when Send switch is pressed, the PIC transmits a series of 40kHz pulses via the ultrasonic transmitting transducer. .operating frequency (4MHz as set by crystal X1) and the number of commands that are processed between each phase of the output signal. Solid objects within the path of this signal reflect it back to the ultrasonic receiving transducer, RX1. These measurements are displayed on the 16-character 2-line LCD (liquid crystal display module). both meters and feets.The transmission and echo conversion process continues for as long as the Send button remains pressed. You can, therefore, pan around a room and just generally view its dimensions until you are ready to accept a measurement. At this moment, releasing the switch will cause the last measurement read to stay on the LCD screen. It will remain there until Send is pressed again, or Recall switch is pressed, or the unit is switched off.While Send is pressed, the sampling rate is normally a little under once per second depending on the mask and distance values.